The present invention relates to a method for carrying out the equipment of a nuclear power plant from its containment building, more particularly to a method for carrying out the exposed equipment of a nuclear power plant from its containment building.
A first background art technique related to a method for carrying out a reactor pressure vessel (hereafter, to be referred to as an RPV), which is one of the exposed equipment, from its containment building is disclosed in Japanese Published Unexamined Patent Application No.6-230188. According to this method, the RPV is lifted up in an air lock prepared on the roof of the containment building, then the air lock is kept in a negative pressure state while both of the air lock and the RPV are moved together.
A second background art technique related to a method for carrying the RPV out is disclosed in the official gazette of Unexamined Published Japanese Patent Application No.8-62368. According to this method, at first a clean room is prepared for covering an opening of the roof of the containment building so as to be adjacent to the building, then the structures in the reactor, the control rod driver housing (hereafter, to be referred to as a CRD housing) and the RPV are united into one so as to be moved together in the clean room, then carried out from the building. The official gazette also describes another method for moving the structures in the reactor, the CRD housing, the RPV, and the xcex3 shield that are united into one in the clean room, then carried out from the building.
A third technique related to a method for carrying the RPV out is disclosed in Japanese Published Unexamined Patent Application No.9-145882. According to this method, the structures in the reactor and the CRD housing are lifted up together with the RPV, then their outer surfaces are covered by a cylindrical shield respectively so as to be sealed as a large block. Then, the block is carried out from the containment building.
Although a method for carrying such an RPV out is described in the first to third background art techniques, neither a procedure nor a method for cutting off such structures as pipes connected to the RPV and none of the methods for carrying out and storing those cut-off structures is described in those techniques.
Under the circumstances, it is an object of the present invention to provide a method that can shorten a working time for carrying out structures disposed outside of the object nuclear power plant equipment and removed so as to carry out the equipment itself.
In order to achieve the above object, the present invention provides an embodiment. The embodiment removes structures of the object nuclear power plant, which is disposed outside the equipment of the plant first, then places those structures removed and covered by a shield respectively in spaces in the equipment, and finally carries out the equipment together with those structures therein out of the containment building.
According to the present invention, therefore, it is possible to place the structures removed from the nuclear power plant in the equipment to be removed and carried out of the containment building, thereby carrying out the equipment together with the structures placed therein from the containment building. Consequently, it is possible to shorten the working time required for carrying out the structures removed from the nuclear power plant so as to remove the equipment significantly. In addition, because those removed structures are placed in the equipment before they are carried out, it is possible to reduce the number of casks used for carrying out these structures.
Furthermore, in order to achieve the above object, the present invention provides another embodiment. The embodiment removes the structures disposed outside the equipment of the object nuclear power plant first, places those removed structures in the equipment, then removes and carries out the equipment covered by a shield out of the containment building.
In order to achieve the above object, the present invention provides further another embodiment. In this embodiment, the structures disposed outside the equipment of the object nuclear power plant are removed first, then they are placed in the equipment. After that, the equipment covered by shield and loaded with the removed structures therein is carried out from the containment building.
In order to achieve the above object, the present invention provides further another embodiment. In the embodiment, the joint of each connection between the reactor pressure vessel and a pipe is plugged while water is filled in the reactor pressure vessel above the joint, then the pipe is cut off outside the reactor pressure vessel and a closing plate is attached to the cut-off portion.
Consequently, the radioactive rays can be shielded by the filled water, so it is possible to protect the workers who cut off the pipes from the exposure more effectively.